Flame-retarded and reinforced ethylene vinyl acetate copolymer with microencapsulated expandable graphite and microencapsulated red phosphorus

Simultaneously elevating fire safety and mechanical property is of great significance in flame retardation of polymers. Herein, a series of ethylene vinyl acetate (EVA) composites flame-retarded by expandable graphite (EG) were prepared and studied respecting their fire-retardant, mechanical, rheological and electrical properties. Results evince that combination of microencapsulated expandable graphite/microencapsulated red phosphorus (MEG/MRP) shows efficient fire-retarding effect on EVA in that adding merely 8 wt.% MEG/MRP can raise the polymer's limiting oxygen index to 26.6 % and UL-94 test to V-0 rating, whereas up to 20 wt.% EG and 10 wt.% EG/MRP are required for EVA to attain V-0 rating, respectively. The high efficiency is caused by more sizeable expansion ratio of MEG and high-quality expanded char resulting from MEG/MRP. Proper crosslinking of EVA matrix can augment strength and elasticity of EVA/MEG/MRP composite without lowering its fire retardance. Overall, the crosslinked EVA/MEG/MRP composite with 8 wt.% MEG/MRP shows good fire safety and mechanical property concurrently in contrast with virgin EVA.